Aircrafts, automobiles, and various other load-bearing systems, devices, vehicles and the like, experience vibrations during operation that may degrade these structures and/or minimize their service life. Vibration damping devices, herein referred to as damping devices, are commonly used to combat these negative effects, by reducing the amplitude of resonant vibration and thereby dissipating the vibrational energy. Polymers and composites are often used as vibration-damping components in these damping devices.
Specifically, passively compliant polymers such as rubber, polyurethane elastomer have been utilized in damping devices. However, these materials typically have their damping properties tailored to a specific range of vibration frequency that cannot be changed once the material is made.
In a given polymer system, the molecular weight and crosslink density of the polymer may impact the thermal mechanical properties of a polymer. For example, an increase in the crosslink density of a polymer can frequently result in a substantial increase in the glass transition temperature of the polymer. Manipulation of the crosslink density of a polymer can evoke a change in the glass transition temperature (Tg) of the polymer. Through an oxidation process, the number of crosslinks in the material can be increased, therefore raising the Tg of the material system. A second process, a reduction reaction, cleaves the crosslinks created in the first process, therefore lowering the Tg of the material back to its original state.
Variable stiffness materials, such as piezoelectric ceramic or polymers, have also been utilized in damping devices. However, these variable stiffness materials require a constant supply of power in order to maintain the damping performance, which is less advantageous from an energy consumption standpoint especially when limited power is available.